| 12 May 2015 04:26 AM |
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Hello all; I am facing problem to enter a simple syntax in ENVI's Band Math to derive proportion of vegetation.
Pv =[(NDVI-NDVImin)/(NDVImax-NDVImin)]2
How would I enter this expression in ENVI. I have NDVI raster with Min value of -0.445443 and Max 0.683279
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MariM
Veteran Member
Posts:2396  
| 12 May 2015 06:59 AM |
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In band math, you assign the bands to variables that are named 'b1', 'b2', 'b3', and so on. So with the below information, it would be something like:
((b1 - (-0.445443)) / (1.128722))^2
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Deleted User
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| 12 May 2015 11:22 PM |
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I am thankful for your prompt anticipation in this regard. Kindly let me know how did you get 1.128722?
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Deleted User
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| 13 May 2015 06:06 AM |
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Nasir Hameed wrote:
I am thankful for your prompt anticipation in this regard. Kindly let me know how did you get 1.128722?
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Deleted User
New Member
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| 13 May 2015 07:36 AM |
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MariM wrote:
In band math, you assign the bands to variables that are named 'b1', 'b2', 'b3', and so on. So with the below information, it would be something like:
((b1 - (-0.445443)) / (1.128722))^2
Please let me know how did you derived 1.128722 in the expression? So I could proceed next step.
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MariM
Veteran Member
Posts:2396
| 13 May 2015 07:38 AM |
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It NDVI Max - NDVI Min that you provided. You could do the actual calculation but I just used the values you provided.
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Deleted User
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| 13 May 2015 07:45 AM |
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That's right. So I have to use minus sign.
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Deleted User
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| 13 May 2015 07:47 AM |
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What about this expression ((b1+0.45443)/(0.683279-0.445443))^2
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Deleted User
New Member
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| 13 May 2015 07:50 AM |
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MariM wrote:
It NDVI Max - NDVI Min that you provided. You could do the actual calculation but I just used the values you provided.
What about this expression ((b1+0.45443)/(0.683279-0.445443))^2
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MariM
Veteran Member
Posts:2396
| 13 May 2015 11:05 AM |
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Would you need to add the last two numbers since the min is negative?
((b1+0.45443)/(0.683279+0.445443))^2
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Deleted User
New Member
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| 14 May 2015 12:42 AM |
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MariM wrote:
Would you need to add the last two numbers since the min is negative?
((b1+0.45443)/(0.683279+0.445443))^2
You are right. You helped me alot. I am so grateful for your generous support. Thank you very much
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